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I was watching a CNR freight train thunder through at a grade crossing today and I couldn't help but notice how much the track was moving up and down under the weight of the freight cars! I've actually seen this before in one of my other favourite train-watching locations.

It wasn't a whole lot different from how my track on my HO layout moves up and down (under the weight of my model trains) when it's not properly glued down or ballasted! This got me thinking, how common is this and how safe is this extra movement or play?

In June, I spent a day helping at one of the heritage railways that I visit. Staff there said they're out doing track maintenance work every week, and have to adjust/fix the ballast, gauge and positioning of the rails, etc. I suspect that this location (near the grade crossing) might need some maintenance?

Thanks,
Rob
I'm not sure I've ever noticed this on a mainline, but it seems common on sidings. I've seen where at a rail joint, one rail will drop each time a wheelset passes over, while th adjacent rail moves much less. Loose fishplate perhaps? Anyway I thought it would be neat to model this. However, even when I used thinner ties on one side of a railjoint and omitted a railjoiner, only a loco was heavy enough to get the one rail to depress. I never attempted it, but here is a thought I had: Using a photo detector to activate a spring loaded device to pull down on a wire soldered to the underside of a rail. Each time a wheelset passes over the detector, the wire is pulled down, releasing immediately, the spring returning the rail. It would be pretty cool for a foreground siding that doesn't see too much traffic, just a setout or two.
jglfan Wrote:I'm not sure I've ever noticed this on a mainline, but it seems common on sidings. I've seen where at a rail joint, one rail will drop each time a wheelset passes over, while th adjacent rail moves much less. Loose fishplate perhaps? Anyway I thought it would be neat to model this. However, even when I used thinner ties on one side of a railjoint and omitted a railjoiner, only a loco was heavy enough to get the one rail to depress. I never attempted it, but here is a thought I had: Using a photo detector to activate a spring loaded device to pull down on a wire soldered to the underside of a rail. Each time a wheelset passes over the detector, the wire is pulled down, releasing immediately, the spring returning the rail. It would be pretty cool for a foreground siding that doesn't see too much traffic, just a setout or two.

Thanks ... it would be interesting to see if this happens a lot at other locations and if it is a major safety risk. I don't seem to have any trouble modeling this -- especially on my newer layout where I haven't yet ballasted or properly glued down all the track sections! Cheers, Rob
The guys at my LHS commented a while back that while they were listening in on the CN radio transmissions one day that they over heard the engineer for the train that had just past them radio in to dispatch that when he rolled through a particular spot he felt the loco lean to the side. Confusedhock:
Rob,That's a normal occurrence..

The track has some give to it especially around the joints so the joint doesn't break from the weight of the train..
Brakie Wrote:Rob,That's a normal occurrence..

The track has some give to it especially around the joints so the joint doesn't break from the weight of the train..

Thanks, it just seemed like quite a distance that it was moving but I'm sure it is normal to some extent. I'll keep watching at other sites when I get a chance. Rob
tetters Wrote:The guys at my LHS commented a while back that while they were listening in on the CN radio transmissions one day that they over heard the engineer for the train that had just past them radio in to dispatch that when he rolled through a particular spot he felt the loco lean to the side. Confusedhock:

That sounds scary ! I hope they're keeping up with their maintenance. Eek Rob
I'm sure that they will check it out and have it repaired. The modular club I belong to used to have our e-board meetings at a restaurant across the parking lot from the Amtrac station on the Santa Fe mainline at Fullerton, and after the meetings we would adjourn track side to watch trains. One day while watching the trains going through, one of the guys noticed a broken rail. He called it in to the reported it to the Amtrac personnel to let the Santa Fe know about the problem, the next month we noticed that the broken rail was welded. Railroads are among the most safety conscious industries in the country, and I presume that it is the same in Canada.
Rob,

I've noticed this movement when setting up temporary loops of track on the basement carpet for my kids. You might be able to model the movement by using a "less supportive" roadbed (like carpet) for a longish section of track (say one length of flex). Drill out the holes in the ties a little larger and loosely secure with track nails to allow up and down movement, but not side to side.

A certain amount of movement is normal (kind of like flex in airplane wings). The rails would have to be immensely strong - and therefore larger and more expensive - if there was to be no movement at all.

Andrew
I say a little bit of give is necessary with any kind of structure that has to bear heavy, immense structural loads. Even the CN tower (like most modern building structures) made out of solid concrete and rebar was/is designed to sway ever so slightly in the wind in order to increase its "life expectancy" as a structure. Something solid, rigid and immovable would wear out faster, collapse or break when subjected to constant forces impacting on its structure.

I'm probably just pointing out the obvious to everyone here. Misngth
MasonJar Wrote:Rob,

I've noticed this movement when setting up temporary loops of track on the basement carpet for my kids. You might be able to model the movement by using a "less supportive" roadbed (like carpet) for a longish section of track (say one length of flex). Drill out the holes in the ties a little larger and loosely secure with track nails to allow up and down movement, but not side to side.

A certain amount of movement is normal (kind of like flex in airplane wings). The rails would have to be immensely strong - and therefore larger and more expensive - if there was to be no movement at all.

Andrew

I would hesitate to use carpet with ho. I think you are liable to get fibers jamming up the works. I think a thin layer of foam rubber with give similar to carpet would replicate the movement of the prototype without creating the problem with the carpet fibers.
Russ,

Right you are! Good point.

Andrew
tetters Wrote:I say a little bit of give is necessary with any kind of structure that has to bear heavy, immense structural loads. Even the CN tower (like most modern building structures) made out of solid concrete and rebar was/is designed to sway ever so slightly in the wind in order to increase its "life expectancy" as a structure. Something solid, rigid and immovable would wear out faster, collapse or break when subjected to constant forces impacting on its structure.

I'm probably just pointing out the obvious to everyone here. Misngth


This is helpful -- I was just thinking of the CN Tower comparison today! Yes, most things or structures do need to have some movement or flex.

Also, FYI, I'm not purposely trying to model this. I was just interested in seeing this "phenomena" in real life and amused at how similar it was to some pre-glued/ballasted areas of my layout.

Cheers,
Rob
Actually we spend most of our time on track work to keep it from moving. Unlike structures made of different materials that have to give, the track is supported to keep it from giving as much as possible. That's why you see tampers on the big roads almost constantly. Even at that it is not unusual for track to pump an inch or so, and as long as both rails pump evenly it isn't a problem.
Jointed rail will pump at the joints, which in most cases are staggered, and this can cause cars to rock sideways until they rock right off the track.
Charlie
My friend Blake and I were at the remnants of Greenville Yard near Jersey City, NJ many years ago. There was still a car float operation. We watched as a GP pulled and pushed cars through some track where the rails lifted off the ties (apparently no spikes) and bowed to almost touch the sill of the boxcars doors. Eek

Mark
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